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Analog Electronics Class Session 1: RC and RL Circuits (Into to Tina Spice)

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## Analog Electronics Class Session 1: RC and RL Circuits (Into to Tina Spice)

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**Analog Electronics ClassSession 1: RC and RL Circuits(Into**to Tina Spice) Sep 1, 2011**Intro to the Class**Class 1: Review RC, and RL Circuits Class 2: Ideal op-amp, Analysis Techniques Class 3: Vosi, Vcm, CMRR, PSRR, Class 4: Aol, Ib, Drift, Output swing Class 5: Power…. Class 6: Noise… This will probably change**Goal of Class**• Intuitive view of analog electronics • Quick analysis by inspection • Use of spice tools • Cover practical considerations • Example: Capacitor temperature drift, voltage coefficients • Fill in gaps in knowledge**Capacitor**Transient Analysis**Instantaneous changes on capacitor voltage are not possible!**This would create infinite current.**Application – Charging Input cap**A simple RC is sometimes used to condition the input to an A/D converter. The table shows the delay required to settle to ½ bit.**Tina Spice – Transient Analysis**Transient Analysis: Looks at signals vs. time. Set the Source: In this example we will use a step input to change the input from 0V to 1V**Press the button to edit the signal.**Choose the amplitude and start time. In this example 1V and 1mS.**This is the result**Use separate curves**Use the curser to check the specific points on the curve.**In this case 1 time constant yields 0.625V as expected.**Capacitor**AC Analysis**Capacitance at dc and High Frequency**Open at Low Frequency and DC Short at High Frequency**Voltage Divider for RC circuit**• At low frequencies the output is equal to the input. • At High frequencies the output is zero (shorted)**Decibels (dB)**• NdB = 20 log (Gain) = 20 log (Vout / Vin) • 20Log(1) = 0, • 20Log(10) = 20 • 20Log(100) = 40 • 20Log(0.1) = -20 • 20Log(0.01) = -40 • Log(0) is not defined • Gain = 10(Ndb/20)**After pole decrease Gain by 20db/dec**After zero increase Gain by 20db/dec One decade before and after pole phase decreases by -45o/decade One decade before and after zero phase increases by 45o/decade Bode Plot**Inductor**Transient Analysis**Transient Simulation for RL Circuits**Change the prosperities of the switch to close and open to demonstrate charge / discharge.**S1 Closed -- Initial Voltage During Charge through R1**S1 Open – Discharge through R2**Inductor**AC Analysis**Inductance at dc and High Frequency**Short at Low Frequency and DC Open at High Frequency**Voltage Divider for LR circuit**• At low frequencies the output is zero. • At High frequencies the output is equal to the input